Homework Board ??????

Radridz3

Hey everyone I have a really basic question. On the HB the·I/O's have 220 ohm resistor array. I know that most the basic schematics on this site have a 220 on them. So I don't use 1 on most of my connections to the I/O's. I have a DIY BS-2 and I didn't include any 220's onboard. Know when I hook up say a LCD or a LED or RTC or whatever I do with these boards should I throw in a 220???????? I'm asking because I'm having issues with my parallax LCD ..I can adjust the backlight in software and turn it on and off but I'm getting nothing for cursor or characters. I have checked the contrast and Metered almost all of it. Voltage adjusts with pot but not viewing anything. So I;m wondering if I ruined the LCD because I didn't protect it from the BS-2 which I didn't think I would have to do....Currently on the DIY board there's no 220 on the RX line. So what'd ya think?????

rixter

The 220 resistors are protecting the BS, not the devices attached to it. Because the HomeWork is generally used as a starter platform, these are installed to prevent new experimenters from toasting the BS if they forget to implement resistors in their projects ot they attach components improperly.

Backlights are generally LED units independent of the LCD portion of the package, so you could be getting results there and the LCD not functioning.

The Parallax LCD has a test mode selectable with switches (both OFF) on the back that you should be able to use to test the display with just power supplied.

Rick

Radridz3

Yeah thanks for the reply, I didn't think it was that ...But I'm really curious how I smoked this LCD it doesn't test at all. It's OK though got another 1 on the daily deal.·

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Post Edited (Radridz3) : 5/12/2009 2:31:39 PM GMT